Sulfated zirconia was synthesized by a one step solvent-free method, directly mixing Zr­(OH)4 and (NH4)2SO4. The entire synthesis process produces no wastewater, which is environmentally friendly. The synthesis factor (mole ratio of (NH4)2SO4:Zr­(OH)4) is the main point to test catalytic activity. Structural properties are characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherms, and inductively coupled plasma (ICP). The acid property is characterized by pyridine-FTIR. The S coverage (×10–6 mol S·m–2)–Lewis acidic sites density (mmol·m–2) relationship in sulfated zirconia reveals that the generation order of Lewis acidic sites is from weak ones to strong ones. Calculation of acid property reveals the positive structural–functional relationship (WL/SL–catalytic activity). Weak Lewis acidic sites (WL) promote the activity toward removal olefins, while strong Lewis acidic sites (SL) speed up the deactivation of catalysts. The superior catalytic performance as well as environmentally friendly synthesis method demonstrates that solvent-free sulfated zirconia has bright application prospects in industry.

A series of sulfated zirconia (SZ) catalysts was synthesized by immersion of amorphous zirconium hydroxide in sulfuric acid of various concentrations (1 to 5 N). These samples were fully characterized by X-ray diffraction (XRD), thermogravimetric analysis and mass spectrometry (TGA-MS), and aqueous sulfuric acid immersion and high temperature oxide melt solution calorimetry. We investigated the enthalpies of the complex interactions between sulfur species and the zirconia surface (∆H sz) for the sulfated zirconia precursor (SZP), ranging from-109.46 ± 7.33 (1 N) to-42.50 ± 0.89 (4 N) kJ/mol S. ∆H sz appears to be a roughly exponential function of sulfuric acid concentration. On the other hand, the enthalpy of SZ formation (∆H f), becomes more exothermic linearly as sulfur surface coverage increases, from-147.90 ± 4.16 (2.29 nm-2) to-317.03 ± 4.20 (2.14 nm-2) kJ/mol S, indicating stronger sulfur specieszirconia bonding.